Selection of salt tolerant alfalfa ( Medicago L.) plants from different varieties and their morfo biological and symbiotic properties analysis

Soils degradation growing in our days is associated with the depletion of their fertility, a result of crop rotation with excessive amounts of mineral fertilizers and chemical plant protection products, as well as it links with widespread worsening climatic conditions and environmental conditions. For this reason, agriculture based on environmentally friendly technologies must be an absolute priority. Legumes can fix atmospheric nitrogen in symbiosis with nodule bacteria and accumulate it in plant biomass. Legumes are unique predecessors for grain crops, as they contribute to the effective restoration of soil fertility by introducing nitrogen into bioavailable form. Pastures based on legumes contribute to the restoration of soils destroyed and excluded from crop rotation, such as desert or saline. In this, the development of pathways to create new productive plant-microbe systems that can grow in adverse conditions, is of great theoretical and practical significance. The objectives of the study was to identify salt-tolerant plants of alfalfa ( Medicago L.), to obtain plants of the I 1 generation by self-pollination approach and to analyse their morphobiological and symbiotic properties in model experiments. The study was performed on 13 tetraploid and diploid varieties of alfalfa, including commercially valuable varieties Soleustoychivaya and Agniya, both of which were tested without rhizobia inoculation and in symbioses with Sinorhizobium meliloti strains. An analysis of the symbiotic activity of alfalfa varieties showed that they were highly responsible to S. meliloti Rm2011 strain inoculation and formed an effective symbiosis under saline conditions. Geographically different varieties were evaluated for the homogeneity according to dry matter (DM) accumulation at 75 mM NaCl without inoculation, and at 100 mM NaCl with inoculation by S. meliloti. Obtained DM data among the studied cultivars significantly changed only in case of symbiosis that was established with the assistance of the dispersion coefficient (D). Plants of salt tolerant phenotype was obtained for diploid M. caerulea and M. falcata species, as well as for tetraploid M. sativa L. varieties Soleustoychivaya and Agniya in microvegetative experiments done at the All-Russian Research Institute for agriculture microbiology (ARRIAM). Selected salt tolerant plants of both varieties were planted further in greenhouse complex (STC) of V.R. Villiams All-Russian Research Institute for Forages. It was found that salt-tolerant plants of Soleustoychivaya and Agniya are characterized by predominantly purple color of flowers, by a twisted form of bean, by relatively high branching and bushy, by later transition to a period of winter rest according to 3-year vegetation trials in the STC. From seeds obtained from tested plants the I 1 plants were grown, which were studied in microvegetative experiments in ARRIAM. Plants I 1 of both varieties were analyzed by DM, by growth rate of above-ground and underground parts, by number of nodules formed in typical (salt-free) conditions and under salinity. As a result, it was found that generation I 1 plants of both varieties were homogeneous or sufficiently homogeneous according to DM data. Not inoculated generation I 1 plants of Soleustoychivaya variety successfully developed in saline conditions (the average increase of DM was 36.92 % in comparison to plants of initial variety). DM of plants I 1 of Agniya variety was, on the contrary, lower than that of the plants of the initial variety in the saline conditions, being 16.55 % less. The high level of interaction specificity of both varieties of generation I 1 plants with strains CIAM1774 or Rm2011, differing in salt tolerance, was assessed by DM. Thus, under salt stress impact the highest values of DM was obtained for Soleustoychivaya variety plants in symbiosis with strain Rm2011 characterizing by S. meliloti s